DEVELOPMENT AND MODULATION OF CALCIUM CURRENTS IN CORTEX

在出生后的早期，哺乳动物的大脑皮质经历了快速的 细胞特性、板层结构和突触的变化 连通性。这些特性的适当成熟对于 大脑功能正常，几种脑部疾病可能反映 发育异常模式(如精神分裂症、癫痫、 抑郁)。其中许多变化对突触的模式很敏感 输入和细胞活动的程度。细胞内的增加 Ca~(2+)水平被认为是激发 行为和突触输入的模式被转化为变化 在突触强度或连接性方面。在成年的皮质锥体细胞中， 几个离子导电体相互作用，形成细胞的活动。 这种相互作用在成体细胞中还不完全被理解，甚至更少 在未成熟的神经元中进行检查。 去甲肾上腺素(NE)和5-羟色胺(5-羟色胺)等神经调节剂激活 G蛋白和第二信使系统改变离子电导和 成年神经元的放电行为。这些发射机系统已经成熟到 与金字塔的固有细胞特性相同的时间周期 细胞，并可能影响皮质的可塑性。我们设计了 钙离子和钙依赖性钾离子特性的实验研究 电流及不同胎龄大鼠去甲肾上腺素和5-羟色胺的作用 感觉运动性皮质锥体神经元。核心假说驱动 我们的工作是NE和5HT具有多重收敛和发散 未成熟和成人新皮质对电压门控性钙电流的影响 锥体细胞。此外，这些影响可能是年龄相关的，因为 钙、钾通道表达的发育性变化及 去甲肾上腺素和5-羟色胺的受体以及钙离子调节的成熟 机械装置。 这项建议的具体目的是：(1)研究个体发育 新皮质神经元中不同的钙电流。(2)确定 去甲肾上腺素和去甲肾上腺素调节钙电流的信号通路 5HT。(3)确定不同钙电流的功能作用 在诱发钙依赖的K+电流和超极化后。我们 将在脑切片准备中使用细胞内记录，完整 急性分离神经元的细胞膜片钳记录， 药物和单细胞信使核糖核酸扩增技术。 从这些实验中得出的数据预计将有助于 理解(1)离子通道的发展和(2)作用 去甲肾上腺素和5-羟色胺对心肌细胞钙电流和细胞整合的调节作用 皮质锥体细胞。这些机制很可能是重要的 在正常皮质功能的发育过程中，以及在疾病中 流程。

During the early postnatal period, the mammalian cortex undergoes rapid changes in cellular properties, laminar structure, and synaptic connectivity. Proper maturation of these properties is essential to normal brain function, and several diseases of the brain may reflect abnormal patterns of development (e.g. schizophrenia, epilepsy, depression). Many of these changes are sensitive to patterns of synaptic input and the degree of cellular activity. Increases in intracellular Ca2+ levels are thought to be an important mechanism by which firing behavior and the pattern of synaptic inputs are translated into changes in synaptic strength or connectivity. In adult cortical pyramidal cells, several ionic conductances interact to shape the activity of the cell. This interplay is incompletely understood in adult cells and even less examined in immature neurons. Neuromodulators such as norepinephrine (NE) and serotonin (5HT) activate G-proteins and second messenger systems to alter ionic conductances and firing behavior in adult neurons. These transmitter systems mature over the same time period as the intrinsic cellular properties of pyramidal cells, and may influence cortical plasticity. We have designed experiments to investigate the properties of Ca2+ and Ca-dependent K+ currents, and the effects of NE and 5HT at various postnatal ages in rat sensorimotor cortical pyramidal neurons. The central hypothesis driving this work is that NE and 5HT have multiple convergent and divergent effects on voltage-gated Ca2+ currents in immature and adult neocortical pyramidal cells. Furthermore, these effects may be age-dependent due to developmental changes in the expression of Ca2+ and K+ channels and receptors for NE and 5HT, as well as in the maturation of Ca2+ regulatory mechanisms. The Specific Aims of this proposal are (1) To investigate the ontogeny of different Ca2+ currents in neocortical neurons. (2) To determine the signalling pathways involved in the modulation of Ca2+ currents by NE and 5HT. (3) To determine the functional roles of different Ca2+ currents in eliciting Ca-dependent K+ currents and after hyperpolarizations. We will employ intracellular recordings in a brain slice preparation, whole cell patch clamp recordings from acutely dissociated neurons, pharmacological agents, and single cell mRNA amplification techniques. Data derived from these experiments are expected to help in the understanding of (1) the development of ion channels, and (2) the actions of NE and 5HT in modulating Ca2+ currents and cellular integration in cortical pyramidal cells. These mechanisms are likely to be important in the development of normal cortical function, as well as in disease processes.